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authorJens Axboe <axboe@fb.com>2016-08-25 08:00:28 -0600
committerJens Axboe <axboe@fb.com>2016-08-29 08:13:21 -0600
commit8d354f133e86dd03ea7885a91df398c55ff699ff (patch)
tree11049556188d8274f98553f924fda66f0754621e /include/linux/blk-mq.h
parent27489a3c827b7eebba26eda0320bb0f100bef167 (diff)
downloadblackbird-op-linux-8d354f133e86dd03ea7885a91df398c55ff699ff.tar.gz
blackbird-op-linux-8d354f133e86dd03ea7885a91df398c55ff699ff.zip
blk-mq: improve layout of blk_mq_hw_ctx
Various cache line optimizations: - Move delay_work towards the end. It's huge, and we don't use it a lot (only SCSI). - Move the atomic state into the same cacheline as the the dispatch list and lock. - Rearrange a few members to pack it better. - Shrink the max-order for dispatch accounting from 10 to 7. This means that ->dispatched[] and ->run now take up their own cacheline. This shrinks struct blk_mq_hw_ctx down to 8 cachelines. Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blk-mq.h')
-rw-r--r--include/linux/blk-mq.h9
1 files changed, 5 insertions, 4 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index d579252e6463..e1544f0f8c21 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -22,11 +22,10 @@ struct blk_mq_hw_ctx {
struct {
spinlock_t lock;
struct list_head dispatch;
+ unsigned long state; /* BLK_MQ_S_* flags */
} ____cacheline_aligned_in_smp;
- unsigned long state; /* BLK_MQ_S_* flags */
struct work_struct run_work;
- struct delayed_work delay_work;
cpumask_var_t cpumask;
int next_cpu;
int next_cpu_batch;
@@ -40,8 +39,8 @@ struct blk_mq_hw_ctx {
struct blk_mq_ctxmap ctx_map;
- unsigned int nr_ctx;
struct blk_mq_ctx **ctxs;
+ unsigned int nr_ctx;
atomic_t wait_index;
@@ -49,7 +48,7 @@ struct blk_mq_hw_ctx {
unsigned long queued;
unsigned long run;
-#define BLK_MQ_MAX_DISPATCH_ORDER 10
+#define BLK_MQ_MAX_DISPATCH_ORDER 7
unsigned long dispatched[BLK_MQ_MAX_DISPATCH_ORDER];
unsigned int numa_node;
@@ -57,6 +56,8 @@ struct blk_mq_hw_ctx {
atomic_t nr_active;
+ struct delayed_work delay_work;
+
struct blk_mq_cpu_notifier cpu_notifier;
struct kobject kobj;
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